The scientific goal of the K23 application is to develop a novel genomic biomarker combination (Serotonin transporter gene (SERT) mRNA expression levels in 5'-HTTLPR-LL genotype carriers) for quantitatively predict recent alcohol consumption levels. The hypothesis for the study was derived from a series of preliminary work by the candidate that first demonstrated a 52-HTTLPR allele based difference in drinking severity using biochemical and pharmacogenetic studies; extending these findings, the next set of preliminary experiments provided evidence for a positive association between SERT mRNA expression levels and retrospectively collected self-reported alcohol consumption amounts, in LL genotype carriers. To prospectively validate the biomarker combination of 5'-HTTLPR-LL genotype and SERT mRNA expression levels, I propose a series of experimentations conducted in two stages during the 5-year K23 period. In stage I, I will recruit a cohort of adult, male and female heavy social drinkers with LL and LS/SS genotypes in equal proportions: Alcohol will be administered to both genotype groups employing a 3x3 Diagram balanced Latin square design for order and sequence in a human laboratory. With the samples collected daily from the participants during the human laboratory experiments, I will perform SERT gene expression assays to assess validity and specificity of the proposed biomarker (Specific aim I),and study genome-wide microRNA expression alterations in response to alternating doses of alcohol to identify microRNAs that regulate 5- HTTLPR allele-based SERT gene transcription levels (Specific aim II). Specific aim II would also help identify novel markers for heavy drinking which is particularly important in case specific aim I is not achieved. Stage II will be performed to test the supplementary aims only upon successful validation of the biomarker. In stage II, I will compare the specificity of the proposed marker with %CDT and EtG (Supplementary aim I) and test the Sensitivity of the SERT biomarker combination to detect amounts of drinking, in archived samples from alcohol dependent individuals, enrolled in treatment clinical trials (Supplementary aim II). If validated, I believe the proposed SERT biomarker combination may aid in developing efficacious medications to treat problem drinking, which is the third leading life-style related cause of death in the U.S. Environment: My environment at the University of Virginia, Department of Psychiatry and Neurobehavioral Sciences is highly supportive for conducting this K23 award. Our department is well committed and recognized for conducting high quality multi-disciplinary research in clinical, translational and basic sciences research. Currently I serve as a junior faculty member at the Division of Neurobiological Studies with over 15 NIH-funded faculty researchers focusing on genetic, biological, pharmacological, and behavioral aspects of various addictions. The three facilities that I will utilize throughout the K3 award period, University of Virginia Center for Addiction Research and Education (UVa CARE), University of Virginia clinical Psychopharmacology research unit (CPRU), and the Neurobiology laboratory, are all housed within our division. My primary mentor on this project is Professor Bankole A. Johnson, who is a leader in the field of medications development for the treatment of addictions and has successfully mentored many junior investigators throughout the past several years to have promising academic careers. Additionally, my training during the award period will be enhanced by a well-established team of co-mentors, including Professor Ming D. Li to further my skills and knowledge in addiction genetics, Dr. Nassima Ait-Daoud with regular consultations on participant related issues, Dr. Jennie Z. Ma on Biostatistical consultations and Senior Biostatistician Xin Qun Wang with data analyses related issues. My potential for productive collaboration with my mentors is evident through our work on NIH funded grants, coauthoring papers, and their support in the development of this K23 application. Candidate: I am a physician scientist interested in studying molecular and genetic mechanisms underlying alcohol dependence and an individuals' personal response to treatment. My past research training in genetic and biochemistry fields have provided me with an excellent foundation in basic sciences research in alcohol addiction. With the award of this K23 proposal, I would be able to develop additional expertise in conducting human laboratory paradigms of alcohol use modeled under controlled conditions, providing me with the unique opportunity to discover how to integrate molecular and biochemical techniques that I have learned during my training, with human psychopharmacological interventions. By utilizing these interventions during the proposed K23 award period, I will realize my short-term career goal of developing an accurate biomarker to measure transient changes in alcohol consumption levels, addressing a critical need in the field of alcohol addiction treatment. My overarching career goal is to improve treatment for alcohol addiction, through targeting molecular genetic mechanisms underlying alcohol addiction to identify new directions in pharmacotherapy. At the end of the proposed five years, through the experience and knowledge that I gain from mentored research projects focusing on human psychopharmacological interventions, coupled with formal course work, seminars, participation in national and international scientific conferences, I will emerge a successful independent translational research scientist with a focus on molecular psychopharmacology.